Mapping the longevity horizon: a 5-wave random-intercept cross-lagged panel analysis of subjective life expectancy, depressive symptoms, functional disability, exercise frequency, and skipped meals in an aging population in Thailand.

OBJECTIVES: To examine within-person longitudinal pathways linking Subjective Life Expectancy (SLE) with depressive symptoms, Activities of Daily Living (ADL) limitations, exercise frequency, and skipped meals in ageing adults in Thailand.
METHODS: Longitudinal data from 5259 older adults across five biennial waves (2015-2024) of the HART study were analyzed using a joint multivariate latent Random Intercept Cross-Lagged Panel Model (RI-CLPM). Robust maximum likelihood estimation was used to account for non-normality, while longitudinally metric-invariant latent item parcels represented depressive symptoms. Measurement error for the single-item SLE indicator was incorporated using an established reliability estimate (α = 0.80). Continuous-time scaling was applied to account for unequal wave spacing. Inverse Probability of Attrition Weighting (IPAW) was used as a sensitivity analysis for potential attrition-related bias.
RESULTS: Model fit was generally acceptable to excellent (robust RMSEA ≤0.051; SRMR ≤0.102). At the within-person level, increases in depressive symptoms consistently predicted subsequent declines in SLE (B = -0.336, SE = 0.055, z = -6.152, p < 0.001). In contrast, cross-lagged associations from SLE to ADL limitations and exercise frequency were not significant after joint latent adjustment (SLE → ADL: B = 0.060, p = 0.255; SLE → exercise: p > 0.05). SLE was also not significantly associated with subsequent skipped meals (p = 0.583). IPAW sensitivity analyses supported the stability of the primary directional associations.
CONCLUSIONS: Within-person increases in depressive symptoms were associated with subsequent declines in SLE, whereas SLE fluctuations did not independently predict subsequent functional, exercise, or meal skipping. These findings suggest that psychological distress may be an important determinant of older adults' subjective longevity expectations.